Example embodiments disclosed herein pertain to headsets. More particularly, example embodiments disclosed herein pertain to acoustic headsets with additional functionality.
There are several common headset types. For example, a “mono voice” headset includes one speaker and one microphone. A “stereo audio” headset includes two speakers only. i.e. it is a standard set of stereo headphones. A “stereo voice” headset includes two speakers and a microphone. A “stereo remote” headset includes two speakers and a multi-button remote. An example of a stereo remote headset is the headset provided with the Apple iPod Shuffle. A “voice only” headset includes a microphone but no speakers.
Many electronic devices use phone jacks for audio connectivity. For example, many cell phones and MP3 players use either a 2.5 mm or a 3.5 mm phone jack for such purposes. A headset includes a complementary phone plug to connect to the electronic device. Phone plugs are also referred to as TRS connectors (tip, ring, sleeve). They are usually cylindrical in shape, typically with three contacts (“rings”), although sometimes with two rings (a TS connector) or four rings (a TRRS connector).
The most common connectors used with multifunction headsets are the 3-ring TRS connectors and the 4-ring TRRS connectors. With the TRS connectors, a 2.5 mm version is used primarily for mono voice and a 3.5 version is used primarily for stereo audio. With the TRRS connectors (both 2.5 mm and 3.5 mm), the fourth ring can be used for one of a mono microphone, wired remote control, or composite video.
FIG. 1 is a schematic diagram of a prior art stereo voice headset. The headset 10 includes a phone plug 12, stereo speakers 14 and 16, a microphone 18 and a high-frequency shunt or “bypass” capacitor 20. Alternatively, an internal bypass capacitor may be integrated with the microphone 18 in which case an external bypass capacitor 20 is not needed. This headset uses a TRRS connector with two rings being used, one each, for stereo speakers, one for ground, and one for a microphone. The rings of all of these connector types are typically made from an electrically conductive metal and are electrically insulated from each other.
FIG. 2 is a schematic diagram of a prior art stereo voice headset 10′ with microphone. The headset 10′ is essentially the same as the headset 10, with the addition of a send/end switch (“button”) 22. In the prior art, the send/end button either shorts across a microphone or is put in series with a microphone to selectively disable the microphone.
FIG. 3 is a schematic diagram of a prior art stereo remote headset. The headset 24 includes the phone plug 12, stereo speakers 14 and 16, and send/end button 22 of headset 10′ of FIG. 2. However, the microphone 18 has been replaced with a wired remote control 26 comprising a number of resistors that can be coupled to ground by switches (“buttons”). Since the resistors of the remote control 26 have different values, pressing different buttons can create distinct voltage drops which can be detected by circuitry, not shown, which is connected to the fourth ring “RMT” of the phone plug 12.
A problem encountered in the prior art is that only so much functionality can be supported by a phone plug. In stereo applications two of the rings are used for the left and right speakers of a headset, while a third ring is coupled to ground. This leaves only the fourth ring to support any other functionality of the headset such as a microphone or wired remote control. As a result, prior art stereo headsets were typically limited to one other function, such as a microphone as shown in FIGS. 1 and 2, or a wired remote control as shown in FIG. 3.
These and other limitations of the prior art will become apparent to those of skill in the art upon a reading of the following descriptions and a study of the several figures of the drawing.